Decoding circuit for a mechanically resonant relay



April 26, 1960 T. J. JUDGE 2,934,636

DECODING CIRCUIT FOR A MECHANICALLY RESONANT RELAY Filed Dec. 24. 1956 INVENTOR.

T.J.JUDGE HIS ATTORNEY MECHANICALLY RESONANT r' 2,934,636 Patented Apr. 26,1960

' DECODING CIRCUIT FOR A MECHANICALLY f RESON ANT RELAY Thomas J. Judge, Rochester, N.Y., assignor to General Railway Signal Company, Rochester, N.Y.

7 Application December 24, 1956, Serial No. 630,260

5 Claims. 7 (Cl. 246-34) The present invention relates to automatic block signal track circuit in advance and by providing appropriate.

apparatus at the entrance or relay end of the track circuit that will respond selectively to the code ratebeing received, multiple proceed aspects may be controlled through the rails.

The usual coded track' circuit has a code responsive track relay which alternately picks up and releases in response to the impulses of energy placed on the track rails and controls the flow of energy to a master decoding transformer. In such-a system, the signal circuits are controlled by'a decoding relay. The decoding relay-is so controlled through the contacts of the track relay' and the master decoding transformer that it will be picked up when codes are received but will release when the track relay is not coding. I

The coded track circuit system to which the present disclosure is applicable does not utilize a master decoding transformer but rather provides signal circuit control by means of decoding apparatus including a mechanically resonant device which when organized as described here-- 45 in will provide a coded track circuit organization which is responsive to a distinct selected code rate,

Included in such decoding apparatus is a mechanically resonant relay structure of'the type and nature disclosed by R. W. Craig, in his application Ser. No. 6l7,056,-filed October 19, 1956, now US. Patent 2,833,884, granted May 6, 1958. Such a mechanically resonant relay structure is capable of detecting codes of a particular frequency by means of a pendulum whose resonant frequency of oscillation is the particularcode frequency to be detected. Such relay has at least two groups of contact members, one group actuated by an armature, such armature acting as a repeater for the track relay, the

aspects alongany given track circuit will be displayed 7 only when the particular code frequency transmitted over that track circuit is the same as the resonant frequency of.- a mechanically resonant relay structure.

- Another object of the present invention is to combine the inherent operative qualities of a resonant relay structure with a circuit organization by means of the synchronous operation of pulsing neutral and resonant contacts for alternately selecting a charging circuit and a discharging circuit for a condenser. The condenser is charged through acircuit exclusive of the decoding relay, but including said resonant and neutral contacts, and is discharged through a circuit including said contacts into the winding of the decoding relay.

Other objects,'purposes and characteristic features of the present invention will be in part obvious from the accompanyingdrawing and in part pointed out as the description progresses.

The single sheet; of drawing is a schematic diagram illustrating the use of decoding apparatus embodying the- 7 present invention as applied to coded' track circuits.

including rails 3.-

other group actuated by a peudulum.- The pendulum operated or resonant contacts are actuated only when the frequency of the track relay response is substantially the same as the resonant frequency of the pendulum member. spond to any code rate put on the track circuit while the pendulum actuatedcontacts will respond to only one particular code rate. When thecode rate is such that the armature and pendulum actuated contacts are operated. in synchronism, a condenser decoding unit is alternately charged and discharged. The discharging circuit includes a decoding relay, a contact of which hasbeen placed in the signal control circuit. 7 7

Therefore, it is one object of the present invention to provide a circuit organization in which certain signal Thus, the armature actuated contacts will re-,

. Rather, than attempting to illustrate the specific construction of parts that would be employed in practice, the illustrations in the drawing are of a schematic type to moreclearly illustrate the principles and mode of operation of the system according to the present invention, the

symbols and being employed in some instances to indicate connections to respective positive and negative terminals of suitable batteries or other sources sive to code frequencies of 75 cycles per minute or more,

for purposes of comparison, tWo code frequencies, i.e. 75 cycles per minute and 180 cycles per minute, have been selected. Depending upon whether the front or back contact 63 is closed in accordance with the energization of relay ZBP, the code transmitting relay CP will be alternately energized and deenergized in accordance with either a .75 or a 180 code rate supplied from suitable code oscillators or the like. 7

Since the coded track circuit assumed in this disclosure lSCOHSldCl'fid in a system of normally clear signaling,

the relays BP, 2BP, etc. are normally picked-up in response to the presence of codes. For this reason, the

relay CP is normally actuated by the clear code rate of 180 cycles-per-minute, and alternately connects the I battery B and limiting resistance R across the track .rails through-front contact 53, and then shunts the track rails through back contact 53. In this way, relay CP is operated in accordance with the proper code rate and theappropriate code rate is thus put on the track circuit At the entrance end of the track section, a track relay TR is connected across the rails and is responsive to and repetitious of the code rate transmitted by the alternate energization and deenergization of the relay CP. For

, purposes of explanation, it Will be-assumed that front contact 63 of relay ZBP has been closed and consequently a code rate applied to the track rails in themanner described above. With 180 code rate applied to the track circuit, the track relay TR will pick up its front contacts 18 and 19 for each on period of the codes acting so that during the off period of the code, contact 34 will remain picked up, and since back contact 18 of the track relay TR is alternately opened and closed, an energizing circuit for the back repeater relay BP is completed from through back contact 18 of relay- TR, contact 34 of relay FP, the winding of relay BP, to When relay BP is energized, its contacts 25 and 26 are picked up and remain up so long as codes are received. It should be noted at this point that the above operation of contact 18 of relay TR along with the subsequent operation of the first repeater relay PP and the second repeater relay BP will be the same for any code rate which may be put on the track rails, for example 75 or 180 cycles per minute.

Likewise, contact ll? of the track relay TR will also be alternately picked up and released in accordance with various applied code rates. Hence, during the on period of the code, front contact 19 of relay TR is closed, and since contact 25 of relay BP is steadily closed during reception of a code, an energizing circuit is completed for the upper winding of the mechanically resonant relay 180TPR from through front contact 25 of relay BP, front contact 19 of relay TR, the upper winding of relay ISQTPR, to

During off periods when the relay TR is deenergized, back contact 19 of relay TR is closed. Since the back repeater relay BP, like the front repeater relay FP, has also been made a slow acting relay, contact 25 of relay B]? will remain steadily closed. Thus, during-each o period of the code, the track relay TR completes an energizing circuit for the lower winding of the mechanically resonant relay l ilTPR from through front contact 25 f relay BP, back contact 19 of relay TR, the lower winding of relay 180TPR, to

A mechanically resonant relay 180TPR, as shown by the drawing, is a double armature relay of the polar stick type, but it could also be a double armature relay which has its armature biased in one position. If the relay 180TPR is of the kind that has its armature biased to one position, obviously it would be necessary to ener gize the windings of relay 180TPR only'during the on periods of the code.

Relay 180TPR has a group of neutral contacts, one contact of which has been shown in this disclosure as contact 42. Such neutral contacts are actuated by the operation of the relay armature and will be pulsed in accordance with any code rate applied to the track rails, similar to contacts 18 and 19 of the track relay TR. Relay 180TPR also has a group of resonant contacts, one contact of which has been shown as contact 41. Such resonant contact is actuated by the oscillation of the pendulum member found in relay 180TPR and will be pulsed only when a code rate corresponding to the resonant frequency of the pendulum member is applied to the track circuit and such pulsing of the resonant contact 41 will have the same frequency as the applied code rate.

With a 180 code rate being applied to the track circuit,

the neutral contact 42 of relay 180TPR and the resonant 180 code frequency. When front contacts 41 and 42 of relay ISOTPR are picked up during the on period, a charging circuit is completed for thecondenser C1 from the terminal of the battery CB, through a current limiting resistor LR, left hand contact 41 of relay 180TPR, the condenser C1, the current limiting resistor ZLR, through front contact 42 of relay 180TPR, to the terminal on the battery CB. This circuit then efiectively' charges the condenser C1 during each on period of the code.

During 01f periods, back contacts 41 and 42 of relay 180TPR are closed and a discharge circuit is completed for the condenser C1 from the side of: the con denser C1, through right hand contact 41 of relay 180'IPR, back contact 42 of relay 180TPR, the winding of a decoding relay 180D, to the negative terminal of the condenser C1. It will be noted-that a portion of the discharge is also applied across the second condenser C2 through resistor 3LR. The purpose of this second condenser C2 is to provide relay 189D with suflicient holding energy during the period when relay 180TPR is again closing its respective front contacts 41 and 42 which will again charge the condenser C1. The portion of discharge connected across the second condenser C2 passes through the condenser C2, through the limiting resistance 3LR, back through the winding of the decoding relay 180D. Hence, the relay 180D'will pick up and remain picked up as long as the relay 180TPR follows a 180 code rate. The inclusion of the condenser C2 along with the limiting resistance 3LR also helps to reduce the sparking at the contacts 41 and 42 of relay 180TPR during the time when the condenser C1 is discharging.

It should be noted at this point that although a code rate of 180 cycles per minute has been used in the present disclosure for the purpose of illustration, a mechanically resonant relay structure which has a resonant frequency other than 180 could be used, as for example, cycles per minute. In this event, the resonant contact group would be responsive only when a corresponding code rate of 120 cycles per minute was applied to the. track circuit; Furthermore, it is possible that more than one mechanically resonant relay could be inserted in the track circuit with appropriate controls connected to the signal aspects to provide added utility to the disclosure.

It is apparent from the above description that the alternate operation of the front and back contacts of the resonant contact 41 and neutral contact 42 of the relay TPR, which operation alternately completes a charging and discharging circuit for the condenser C1 during respective on and off periods, will cause the decoding relay 180D to have its winding intermittently energized so. that it remains steadily picked up only during the reception of a 180 code.

When the relay 180D is energized, it closes its front contact 35 and since front contact 26 of the back repeater relay BP is already closed, as described above in connection with the discussion of the relay BP, an ener gizing circuit is complete for one signal aspect from through front contact 26 of relay BP, front contact 35 of relay 180D, aspect G of the signal, to This signal aspect G has been arbitrarily chosen as the clear signal normally having the color green. Obviously, the energizing circuit for this signal aspect will remain completed as long as the code being transmitted over the track circuit remains at 180 cycles per minute. However, once the code changes from the 180 code rate the decoding relay 180D will be deenergized, and remain deenergized, thereby closing its back contact 35 and completing an energizing circuit for a second signal aspect. from through front contact 26 of relay BP, back contact 35 of relay 180D, aspect Y of the. signal, to This signal aspect Y has arbitrarily been chosen as the caution aspect normally having the color yellow. When this signal aspect Y is energized, it would thus be an indication that some code rate is being applied to the particular track circuit, but that particular code rate is at a rate other than 180 cycles per minute.

Considering, therefore, in contrast to the operation of the track circuit during a period when a code rate of 180 is being applied, the operation when a code rate other than 180, such as 75 cycles per minute, is being applied to the track circuit. As stated before, the track relay TR and its corresponding repeater relays PP and HP will operate in precisely the same manner as discussed above relative to the application of a 180 code rate. Further, the mechanically resonant relay 180TPR will have its windings alternately energized in a manner as above described. The critical distinction, however, lies with operation of the resonant contact 41 of the relay 180TPR. Since we have.

assumed that the resonant frequency of the pendulum member which actuates the resonant contact group is 180 cycles per minute, the pendu um will not actuate the resonant contact group when the code rate being applied to the track circuit is 75 cycles per minute, Thus, the operation of the contacts 41 and 42 will necessarily be out of phase or nonsynchronous and the charging circuit for the condenser C1 will not be completed. Hence, the decoding relay 180D will not be energized and its front contact 35 will not be closed. Since, therefore, back contact 35 of relay 180D remains closed, the circuit described above for the second signal aspect-will remain complete showing that a code is being applied to the track circuit, but that such code is at a rate other than 180 cycles per minute. When there is no code being transmitted along the track circuit, contact 53 of the code transmitting relay CP will be down and no energy will be supplied to the track circuit. Obviously, under this condition neither the track relay nor any of the related repeater relays will be energized. Hence, back contact 26 of the back repeater relay BP will remain closed completing an energizing circuit for a third signal aspect from through back contact '26 of relay BP, aspect R of the signal, to This signal aspect R has been arbitrarily chosen as the stop, signal normally having'the color red. It can beseen from the above description that the insertion of a resonant contact into a track circuit which utilizes a condenser decoding unit rather than a master decoding transformer permits the various signal aspects to be distinctly controlled according to a particular code frequency. Further, it will be noted that the. circuit disclosed herein is inherently checked due to the fact that all portions of the shunt circuit are used for normal operation. This shunt circuit insures that the relay 180D will not be operated intermittently during the transition period of a change in code rate.

A further check feature in the organization has been provided by making the relay 180D a neutral biased relay to insure that the relay 180D will. not be falsely engaged. For example, during continuous operation of the organization it is possible, since metal-to-metal contacts are used on code following relays, that left contact 41 and back contact 42 of relay 180TPR, respectively, could be welded closed by metal transfer. Such metal transfer is an ever present problem where metal-to-metal contacts are used in the make-up of the decoding contacts. If such event should occur in the circuit organization shown and described in the present disclosure, and if the condenser Cl breaks down at any time thereafter, an energizing circuit will be closed from the terminal of the battery CB through the limiting resistor LR, left contact 41 of relay 180TPR, condenser C1, the windings of relay 180D, back contact 42 of relay 180TPR, to the terminal of battery CB, thereby falsely energizing the relay 180D. Thus, in order to prevent such false energization, relay 180D has been made a neutral biased relay so that any energizing current provided by a circuit as just described above would tend to force the contact 35 of relay 180D down, preventing the clear signal aspect from being indicated.

Having thus described one specific embodiment of the invention disclosed herein for providing distinctive control to a track circuit using a mechanically resonant relay structure, and more specifically, a decoding circuit requiring synchronous operation of a combination of resonant and neutral contacts for energizing various signal control circuits, it is to be understood that the specific embodiment disclosed herein has been shown for illustrative purposes and to facilitate in the disclosure, and is not intended to limit the number of forms which it may assume, since it is to be understood that various modifications, adaptations, and alterations may be applied to the specific forms shown to meet the requirements of practice, without in any manner departing from the spirit or scope of the present invention.

' What I claim is:

1. In a coded track circuit organization for railroads, a section of track having its ends insulated from adjoining sections, a source of energy anda limiting resistor connected in series with the track rails and located at one end of said section, multiple coding means at said' one end for at times cooperating with said source of energy to energize said track rails with a selective code frequency, a track relay connected in series with the track rails and located at the other end of said section, a resonant relay having at least one resonant contact and one neutral contact, circuit means for energizing said resonant relay in accordance with the actuation of said track relay, a condenser charging circuit means including a source of energy, a limiting resistor and'one each of said resonant and neutral contacts, another circuit meansineluding a decoding relay in combination with said condenser charging circuit means for at times energizing said decoding relay when said resonant and neutral contacts of said resonant relay are actuated harmoniously with a selected code frequency, a first relay with slow release characteristics having its winding energized when said track relay is energized, a second relay having its windings energized when said track relay is deenergized, said second relay having one contact cooperating with said circuit means for at times energizing said resonant relay I in accordance with the actuation of the track relay, and

signaling circuit means controlled in accordance with the distinct actuation of said second relay and said decodingrelay all in a manner dependent upon said code frequency.

2..In a coded track circuit signaling system for a stretch of railway track including a'track section, a coded track circuit including the track rails of said track sectron, and code transmitting and receiving apparatus at the respective ends of the section, said code transmitting apparatus at one end of the track section being effective to apply code pulses to the track rails of said track sec tion at selected rates, and said code receiving apparatus at the other end of'the track section including a mechanically resonant relay energized intermittently at a rate in accordance with the rate of code pulses received through the track rails of said track section, said mechanically resonant relay having independent'neutral and resonant contacts, said neutralcontact having first and second positions to which it is actuated alternately for whatever code rate is received through the track rails, and said resonant contact having first and second positions to which it is actuated alternately only upon reception through the track rails of pulses at a predetermined rate corresponding to the resonant frequency of said mechanically resonant relay, a condenser, a circuit for charging said condenser including in series said resonant contact in said first position and said neutral contact in said first position, a decoding relay, a first circuit for discharging said condenser including in series said neutral contact of said resonant relay in said second position and said resonant contact of said resonant relay in said second position and the winding of said decoding relay, and a second circuit for discharging said condenser including in series said resonant contact of said resonant relay in said second position and neutral contact of said resonant relay in said first position, said second circuit for dis charging said condenser being exclusive of the winding of said decoding relay.

. 3. In a coded track circuit signaling system for a stretch of railway track including a track section, a coded track circuit including the track rails of said track section and code transmitting and receiving apparatus at the respective ends of the section, said code transmitting apparatus at one end of the track section being effective to apply code pulses at selected rates to the track rails, and said code receiving apparatus at the other end of the track section including a mechanically resonant relay energized intermittently at a rate in accordance with 7 the rate of code pulses received through the track rails, said mechanically resonant relay having independent neutral and resonant contacts, said neutral contacts being actuated for whatever code rate is received through the track rails of said track section and said resonant contacts being actuated only upon reception through the track rails of said track section of pulses at a predetermined rate corresponding to the resonant frequency of said mechanically resonant relay, a decoding relay, a condenser, a circuit for charging said condenser including in series one of said resonant contacts and one of said neutral contacts of said resonant relay, a circuit for discharging said condenser including in series another of said resonant contacts and another of said new tral contacts of said resonant relay and the winding of said decoding relay, and means exclusive of the winding of said decoding relay for discharging said condenser when said neutral contacts are actuated out of correspondence with the actuation of said resonant contacts, whereby the condenser is discharged immediately upon a shift in the track code from a rate corresponding to the resonant frequency of said resonant relay to some other frequency which results in failure to further energize the decoding relay by the discharge of the condenser.

4. In a coded track circuit signaling system for a stretch of railway track including a track section, a coded track circuit including the track rails of said track section and code transmitting and receiving apparatus at the respective ends of the section, said code transmitting apparatus at one end of the track section being effective to apply code pulses at selected rates to the track rails, said code receiving means at the other end of the track section including a code following relay connected in series with the track rails of said track section operable at a rate in accordance with the rate of the code pulses received through the track rails, a mechanically resonant relay of the magnetic stick type having independent neutral and resonant contacts, said neutral contacts being actuated for Whatever code rate is received through the track rails and said resonant contacts being actuated only upon reception through the track rails of pulses at a predetermined rate corresponding to the resonant frequency of said mechanically resonant relay, circuit means for energizing said resonant relay with one polarity or the other in accordance with the respective picked up. or

dropped away position of said code following relay, a condenser, a circuit for charging said condenser including in series one of said resonant contacts and one of said neutral contacts of said resonant relay, a decoding relay, and a circuit for discharging said condenser including in series another of said resonant contacts and another of said neutral contacts of said resonant relay and the winding of said decoding relay, whereby the energization of said decoding relay is dependent upon correspondence between the rate of operation of said neutral contacts and the rate of operation of said resonant contacts.

5. In a coded track circuit signaling system for a stretch of railway track including a track section, a coded track circuit including the track rails of said track section and code transmitting and receiving apparatus at the respective ends of the section, said code transmitting apparatus at one end of the track section being effective to apply code pulses at selected rates to the track rails, and said code receiving apparatus at the other endlof the track section including a mechanically resonant relay energized intermittently in accordance with the rate of code pulses received through the track rails, said mechanically resonant relay having independent neutral and resonant contacts, said neutral contacts being actuated for whatever code rate is received through the track rails and said resonant contacts being actuated only upon reception through the track rails of pulses at a predetermined rate, a decoding relay, a condenser, a circuit for charging said condenser including in series one of said resonant contacts and one of said neutral contacts of said resonant relay, and a circuit for discharging said condenser including in series another of said resonant contacts and another of said neutral. contacts of said resonant relay and the winding of said decoding relay, whereby the energi zation of said decoding relay is dependent upon correspondence between the rate of operation of said neutral contacts and the rate of operation of said resonant contacts.

References Cited in the file of this patent UNITED STATES PATENTS 1,997,477 Warnke Apr. 9, 1935 2,607,001 Jerome Aug. 12, 1952 2,659,786 Hufnagel Nov. 17', 1953 

